Gyrocompass starting system



United States Patent 3,550,104 GYROCOMPASS STARTING SYSTEM Makoto Hashii, 126 Kamimeguro l-chome, Meguro-ku,

Tokyo, Japan, and Shin-Ichi Kawada, 943-26 Fukayamachi, Totsuka-ku, Yokohama, Japan Filed Apr. 6, 1967, Ser. No. 628,956 Claims priority, application Japan, Apr. 11, 1967, 41/ 32,702 Int. Cl. G08b 23/00 US. Cl. 340-213 2 Claims ABSTRACT OF THE DISCLOSURE An automatic starting system for a shipboard gyrocompass in which a time switch functions to connect the gyrocompass to its power supply several hours in advance of the departure time for the ship in order that the gyro compass will have been brought up to its operating speed by the time the ship sails. The starting system also includes an alarm mechanism responsive upon a failure in the power supply after the starting time.

This invention relates to a gyrocompass starter, and more particularly an improvement of in an automatic starter for a marine gyrocompass.

Usually, the period of north-seeking movement of a marine gyrocompass is somewhere between 70-90 minutes. Therefore, approximately three to four hours are required from the time of switching on until the gyrocompass is ready for use. The navigator of a ship, for

I this reason, makes it a rule to start the gyrocompass three or four hours before departure of the ship.

This is, however, a very inconvenient practice since the navigator is occupied very much before the ships departure, and to start the gyrocompass as necessary involves a considerable attention. It, then, the gyrocompass is provided with an automatic means to start it at any desired time, and also with an alarm to give warning when the automatic starting is impossible due to power failure or other unexpected reasons, this will relieve the navigator from one of his tasks and will enable him to devote his time for other duties.

One object of this invention is to obtain a system capable of starting a gyrocompass automatically.

Another object of this invention is to obtain a system which starts a gyrocompass automatically, and further, which gives alarm signals if a failure exists in the power supply to the gyro compass at the time of starting.

A further object of this invention is to obtain a system which starts a gyrocompass automatically, gives alarm signals when a failure exists in the power supply to the gyrocompass at the time of starting, and moreover, which stops unnecessary alarm signal when the power failure continues to exist for certain time, while changing over the system itself simultaneously to a condition waiting for recovery from the failure, i.e., a condition which is ready to send signals when the failure is removed.

Other objects, features and advantage of this invention will become apparent from the descriptions taken in conjunction with the accompanying drawing.

The attached drawing is an electrical circuit diagram illustrating an example of the starter covered by this invention.

To explain the principle of the invention, in reference to the drawing, 1 is the master gyrocompass, 2 is the three-phase A.C. ships supply source, 3 is the manual/ automatic changeover switch, 4 is the time switch, and 5 is the solenoid circuit switch, respectively. While the electric source 2 is ordinarily 5060 c.p.s. low-frequency commercial type supply, the gyrocompass, for its high-speed revolution, requires high frequency source (200-400) c.p.s.). Consequently, the rectifier 6 and the inverter 7 are connected between the electric supply 2 and the gyrocompass 1. In other words, the 3-phase low frequency supply from 2 is converted once into direct curent by the rectifier 6, whose output is then supplied into the inverter 7 usually as a direct current of 70 volts. The output of rectifier, in addition, is also distributed to a number of the repeater compasses and other units. The inverter converts the DC. 70 volts again into A.C. 200-400 c.p.s. and this high frequency output is supplied into the gyrocompass 1. The solenoid circuit switch 5 has the solenoid actuator coil 51, and closes when energized, but the switch is open when the coil is not energized.

The changeover switch 3 has a common contact d as well as three transfer contacts e, f and g. The contact e is for 00?, f is for manual, and g is for automatic, respectively. The time switch 4 has two sets of contact 41 and 42. The switch can be set at any time desired so that the sets of contact perform change-over operation simultaneously after an interval of any desired time. Each set of contacts 41 and 42 has a common contact 0, a contact b which is normally closed but opens at a set time, and also a contact a which is normally open but closes at a set time. In this drawing, the contact b of 41 is not in use.

The common contact d of the switch 3 is connected to one of the phase lines of supply 2 through the coil 51 of the solenoid circuit switch 5, whereas the contact f is connected to another of the phase lines of supply 2. The contact g is connected to the same phase line as that of 1 through the contacts 41 a-c of the time switch 4. The contact e is connected off. In order to start the gyrocompass manually, the switch 3 is changed over from e to f at a suitable time, three to four hours before the ships departure. Then the coil 51, energized between the two phase lines of the supply 2, causes the switch 5 to close. The gyrocompass 1 starts immediately since the high frequency current is supplied to it from the supply 2 through the rectifier 6 and the inverter 7, and is ready for use three to four hours thereafter. In order to start the gyrocompass 1 automatically at a suitable pre-determined time, the time switch 4 is set to the time and the switch 3 is changed over from e to g. Although the contacts 3 d-g are closed, the coil 51 is not energized since the contacts 41 a-c are still open. At the preset time, the contacts 41 a-c close and energize the coil 51. The current is supplied to the gyrocompass 1 which in turn starts automatically. Simultaneously with the closing of contacts 41 a-c, the other set of contacts 42 changes over from b to a.

The relay 8, which serves to detect failure of supply 2 or other failures of the power input to the gyrocompass, such as breakdown of supply lines, is connected between the two lines of direct current supply from the rectifier 6 to the inverter 7 in the drawing. The relay has a common contact 0 and changeover contacts a, b. The contacts bc of relay 8 are closed normally or when no voltage exists, and change over to close the contacts a-c when in operation, i.e. when 13. sufiicient voltage exists. The alarm 11, in series to one of the contacts a, b of the relay 8 as well as to one of the contacts 42a, b of the time switch 4, is connected to a stable power supply, such as the battery 10, which is independent from the ships supply 2. In this invention, moreover, a changeover switch 9 is inserted between the contacts a, b of relay 8 and contacts 42 of the time switch 4.

The changeover switch 9, in the drawing, has one pair of contacts h. k connected to the contacts 42 of the time switch 4, and two pairs of contacts m, n and p, q connected to contacts a, b of the relay 8, respectively. The contacts m, q and n, p are interconnected in a way that the switch 9 is in fact a reverse changeover switch. When the movable contactor of the switch 9 is turned in the right side as shown in the drawing, b, a of the contact 42 are connected to the contacts a, b of the relay 8 through the contacts h-m and kp of the switch 9. If the movable contactor is turned in the left, the connection is reversed, i.e. b, a of the contact 42 are connected to the contacts b, a of the relay 8 through the contacts hn and kq of the switch 9, respectively.

In order to start the gyrocompass automatically, with the movable contactor of the switch 9 turned in the right as shown in the drawing, the switch 3 is changed over from e to g, shortly before or after the time switch 4 is set at a desired time. In this condition, since the coil 51 is not energized yet, power is not supplied to the gyrocompass 1 nor the relay 8 is energized and the movable contactor is in the [1-0 side of the contacts. Therefore, 17-0 of the contact 42 is closed, but the contacts ac of the relay 8, connected to 42, is open, whereas the contacts [1-0 of the relay 8 is closed but ac of the contact 42, connected to the relay, is open. Consequently, the circuit of alarm 11 is not closed. As the time set at the time switch 4 comes, both of its movable contactors are reversed and in the contact 42, b-c opens and ac closes. Simultaneously, however, ac of the contact 41 closes to energize the coil 51 which in turn closes the circuit switch 5 to start the gyrocompass 1. At the same time, the relay 8 is also energized, and its movable contactor is reversed from left to right to cause the contacts bc to open and ac to close. In other words, reversal of the contact 42 almost coincides with that of the contacts of relay 8, so that the circuit of the alarm 11 still remains open.

If, however, sufiicient voltage does not exist at the output side of the rectifier 6 due to power failure or other reasons, the gyrocompass 1 is not in the starting condition, and the relay 8, not energnzed, is closed between the contacts b-c and open between the contacts ac. Since in this case the circuit is closed between the contacts 42 ca through k-p of the switch 9 to 12-0 of the relay 8, the alarm '11 is energized by the power supply 10 and gives warning. Assuming that the initial starting operations have been accomplished without failure as described previously, any occurrence of power failure in the later stage will de-energize the relay 8 whose contacts will be reversed. This also closes the circuit of the alarm 11 and the alarm is given.

Since the alarm will continue to operate so long as the failure exists, it is desirable to stop it. In this case, when the switch 9 is turned in the left, the circuit of alarm 11 opens as the interconnections between the contacts a, b of the relay 8 and the time switch contacts 42-a, b, are reversed. In other words, because the contacts h and n, k and q are now connected, the contact 42 c-a, now closed, is connected to the contact a of the relay 8 through the contacts kq. The contacts ac are now open, so the circuit of alarm 11 is also opened. This prevents disagreeable continuation of the alarm.

Moreover, this condition is ready to give an automatic signal whenever the power or other failure is corrected. Supposing that the failure no longer exists after a given period, the relay 8, again energized, reverses the contacts to close ac. This closes the circuit from the contacts 42 ca to kg through ac of the relay 8 and energizes the alarm 11, now indicating that the power failure has been removed. As the switch 9 is turned to the right again, the signal stops and the system returns to the condition of power failure monitoring.

In order to start the gyrocompass manually, the time switch 4 is left as it is, and the switch 3 is turned on from e to 1, but the movable contactor of switch 9 must be turned to the left at the same time. To explain this, closing of the contacts [1- of the switch 3 energizes the coil 51 to close the circuit switch 5, and the gyrocompass 1 starts. The relay '8 is simultaneously energized and the contacts ac also close, but the contact a, connected to the contact 42-a (which is now open) through the contacts gk of the switch 9, prevents the alarm 11 to operate. Then, if a failure de-energizes the relay 8 to close the contacts bc, the circuit is closed from the relay to the contacts 42b-c (which are now closed) through the contacts n-h of the switch 9 and the alarm 11, energized, gives warning signal. The operation thereafter is similar to that of the automatic starting previously described. The switch 9, when turned to the right, stops the alarm and places the system for a condition to wait for recovery of the power supply. As soon as the failure is corrected, the alarm 11 operates to give signal. The switch 9, when turned again to the left, stops the alarm 11 and the circuit is ready for sending alarm if the power supply fails.

The system may be slightly modified by removing the contact f of switch 3, namely substituting switch 3 by an ordinary on-off switch. In this case, the time switch 4 is so designed that the contacts 41a-c and 4'2ac are usually closed. The contacts open when the switch is set at a desired time and close again when the set time comes and the switch operates. For manual starting, consequently, the switch 3 is turned on from c to g with the contacts 4111-0 and 42ac in the closed position. The switch 9 is normally turned to the left and is turned to the right side when the gyrocompass is started. In case of the automatic starting, the switch 3 is turned on from 2 to g after the time is set on the time switch 4. The switch 9 is normally turned to the left, but is reversed to the right, when the time switch is set to a desired period.

If electric capacity of the gyrocompass is sufficiently small, the switch 3 may be connected directly to the power supply of gyrocompass 1, eliminating the circuit switch 5. When high frequencies are used for the ships supply 2, or if the gyrocompass does not require high frequency supply, the rectifier 6 and the inverter 7 may be omitted. Also, instead of the rectifier 6 and the inverter '7, it is possible to utilize any kind of converter capable of converting A.C. 60 cycle directly into any type of high frequency power supply. The feeding terminal of the relay 8 may be located at any convenient point, such as, for example, on the A.C. output side of the ininverter 7.

This invention provides a means of automatic starting of gyrocompass at any desired time, and also of automatic alarm for electric power failure. The invention ont only relieves the navigator from complicated work for starting of gyrocompass, but it provides, by means of the switch 9, possibility of stopping unnecessary continuation of failure signal, and a means to make simple change-over of failure alarm and signal for restoration of the normal power supply. These features provide a very convenient mechanism for starting the gyrocompass.

What is claimed is:

1. In a starting system for a gyrocompass, the combination comprising an electrical power supply source, an electrical circuit extending between said power supply source and gyrocompass, an alarm, circuit means for connecting said alarm to an energizing source, said alarm circuit including first relay means responsive upon a failure of said power supply source for closing said alarm circuit to give an alarm, a time switch, second relay means controlled by said time switch for closing said electrical circuit between said power supply source and gyrocompass and third relay means also controlled by said time switch and included in said alarm circuit, said third relay means serving to hold said alarm circuit in an open condition until said time switch has functioned to actuate said second relay means and to thereafter condition said alarm circuit for closure upon operation of said first relay means.

2. A gyrocompass starting system as defined in claim 1 and which further includes change-over switch means connected into said alarm circuit and having its contacts interconnected with the contacts of said first and third References Cited ifiiir r ui fii 513521 1 322; i id ciifigi i vi $355? 13%: UNITED STATES PATENTS is shifted from a first position to a second position and 1301014 4/1919 Sperry 340*2483 to simultaneously condition said alarm circuit for re- 1,527,932 2/1925 Sperry closure upon restoration of power to said gyrocompass 0 1,573,801 2/1926 Brown 340*248 trom said power supply source, and said alarm clrcult THOMAS B- H ABECKER, Primary Examiner is opened a second time when said change-over swltch means is shifted back to its first position from said sec- US. Cl. X.R. 0nd position. 10 340248, 309.1 

